It all starts with the NORAD radar system called the North Warning System. This powerful radar system has 47 installations strung across Canada’s North and Alaska. NORAD makes a point of checking the radar closely for indications of Santa Claus leaving the North Pole every holiday season. The moment our radar tells us that Santa has lifted off, we begin to use the same satellites that we use in providing air warning of possible missile launches aimed at North America.
Satellites
These satellites are located in a geo-synchronous orbit (that’s a cool phrase meaning that the satellite is always fixed over the same spot on the Earth) at 22,300 miles above the Earth. The satellites have infrared sensors, meaning they can see heat. When a rocket or missile is launched, a tremendous amount of heat is produced - enough for the satellites to see them. Rudolph’s nose gives off an infrared signature similar to a missile launch. The satellites detect Rudolph’s bright red nose with no problem.
https://www.noradsanta.org/
Now I want to know how hot Rudolph’s nose would need to be such that its radiation could be picked up by these satellites.
I am sure it would still be very hot but I wouldn’t be surprised if it was colder than one thinks.